Displaying publications 1 - 20 of 47 in total

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  1. Hafidh RR, Hussein SZ, MalAllah MQ, Abdulamir AS, Abu Bakar F
    Curr Cancer Drug Targets, 2018;18(8):807-815.
    PMID: 29141549 DOI: 10.2174/1568009617666171114144236
    BACKGROUND: Citrus bioactive compounds, as active anticancer agents, have been under focus by several studies worldwide. However, the underlying genes responsible for the anticancer potential have not been sufficiently highlighted.

    OBJECTIVES: The current study investigated the gene expression profile of hepatocellular carcinoma, HepG2, cells after treatment with Limonene.

    METHODS: The concentration that killed 50% of HepG2 cells was used to elucidate the genetic mechanisms of limonene anticancer activity. The apoptotic induction was detected by flow cytometry and confocal fluorescence microscope. Two of the pro-apoptotic events, caspase-3 activation and phosphatidylserine translocation were manifested by confocal fluorescence microscopy. Highthroughput real-time PCR was used to profile 1023 cancer-related genes in 16 different gene families related to the cancer development.

    RESULTS: In comparison to untreated cells, limonene increased the percentage of apoptotic cells up to 89.61%, by flow cytometry, and 48.2% by fluorescence microscopy. There was a significant limonene- driven differential gene expression of HepG2 cells in 15 different gene families. Limonene was shown to significantly (>2log) up-regulate and down-regulate 14 and 59 genes, respectively. The affected gene families, from the most to the least affected, were apoptosis induction, signal transduction, cancer genes augmentation, alteration in kinases expression, inflammation, DNA damage repair, and cell cycle proteins.

    CONCLUSION: The current study reveals that limonene could be a promising, cheap, and effective anticancer compound. The broad spectrum of limonene anticancer activity is interesting for anticancer drug development. Further research is needed to confirm the current findings and to examine the anticancer potential of limonene along with underlying mechanisms on different cell lines.

  2. Abbasi Pirouz A, Abedi Karjiban R, Abu Bakar F, Selamat J
    Toxins (Basel), 2018 09 06;10(9).
    PMID: 30200553 DOI: 10.3390/toxins10090361
    A novel magnetic graphene oxide modified with chitosan (MGO-CTS) was synthesised as an adsorbent aimed to examine the simultaneous removal of mycotoxins. The composite was characterised by various procedures, namely Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and a scanning electron microscope (SEM). The adsorption evaluation was considered via pH effects, initial mycotoxin concentration, adsorption time and temperature. Adsorption isotherm data and kinetics experiments were acquired at the optimum pH 5 fit Freundlich isotherm as well as pseudo-second-order kinetic models. The thermodynamic results indicated that the adsorption of the mycotoxins was spontaneous, endothermic and favourable.
  3. Abu Bakar, F., Salleh, A.B., Razak, C.N.A., Basri, M., Ching, M.K., Son, R.
    MyJurnal
    Biochemical analysis was carried out for pH profiles, freshness in terms of K-values, amino acids profiles, total volatile bases (TVB), total volatile acids (TVA) and biogenic amines for fresh and preserved Macrobrachium rosenbergii. Results showed that pH profiles of Macrobrachium rosenbergii explain the inability of this parameter to be used to evaluate the quality of Macrobrachium rosenbergii. Thus changes in pH profiles of Macrobrachium rosenbergii should be combined with indicators such as total volatile acids and total volatile bases. Total volatile acids of the shrimps increased steadily in small amounts throughout the storage period. A rapid increase in TVB at 100C was detected due to the increase in total aerobic bacteria at elevated temperatures. The microbial activities caused the decrease in the amino acids arginine, lysine and histidine which correlated well with the increase in the corresponding biogenic amines such as putrescine, cadaverine and histamine respectively. Preservatives used in this study controlled the production of these biogenic amines without significantly altering the pH of preserved shrimp.
  4. Chong CY, Abu Bakar F, Rahman RA, Bakar J, Zaman MZ
    J Food Sci Technol, 2014 Jun;51(6):1118-25.
    PMID: 24876644 DOI: 10.1007/s13197-012-0621-3
    Biogenic amines formation in Indian mackerel of tropical region was investigated during storage at ambient (25-29 °C) and ice temperature (0 °C) in relation with changes of amino acids content and amines forming bacteria. All amines increased significantly during storage at two temperatures except for spermidine and spermine. Histamine concentration of 363.5 ppm was detected after 16 h stored at ambient temperature. Aerobic plate count of fish stored at ambient temperature reached 6.98 log CFU g(-1) after 16 h, close to the upper limit (7 log CFU g(-1)) suggested by International Commission on the Microbiological Specifications for Foods (ICMSF). However, proper icing procedure retarded the formation of histamine effectively, resulting only 8.31 ppm after 16 days of ice storage. Aerobic plate count of 5.99 and 7.72 log CFU g(-1) were recorded for fish stored in ice after 16 days and ambient temperature after 20 h, respectively. Histamine exhibited high correlation with histidine (r(2) = -0.963, P  0.05). As storage time progressed, the amines forming bacteria grew significantly except for that stored in ice.
  5. Abu Bakar F, Sazliyana Shaharir S, Mohd R, Mohamed Said MS, Rajalingham S, Wei Yen K
    Arch Rheumatol, 2020 Jun;35(2):205-213.
    PMID: 32851369 DOI: 10.46497/ArchRheumatol.2020.7405
    Objectives: This study aims to assess the self-reported work productivity and activity daily living (ADL) impairment among Malaysian patients with systemic lupus erythematosus (SLE) and to examine their associated factors.

    Patients and methods: This cross-sectional study included 167 SLE patients (21 males, 146 females; mean age 38.2±9.8 years; range, 20 to 60 years) recruited from the outpatient Rheumatology and Nephrology clinics. Face-to-face interviews were conducted to record patients' socio- demographics (age, sex, ethnicity, marital status, and occupation) and SLE disease characteristics (system involvement, age onset, and presence of organ damage). Disease activity was assessed using the Systemic Lupus Erythematosus Disease Activity Index-2000 (SLEDAI-2K). Short form 36 (SF-36) was used to determine health-related quality of life (HRQoL) while Work Productivity and Activity Impairment (WPAI) questionnaire was used to assess the four domains of absenteeism, presenteeism, overall work productivity, and non-work related ADL impairment. Univariate analyses and multivariable regression analysis examined the association of demographic variables, SLE disease characteristics, and activity with reduced HRQoL and WPAI scores.

    Results: The majority of the patients were Malays (59.3%), followed by Chinese (34.7%) and Indian (3.6%) patients. More than two-thirds of the patients reported some degree of impairment in their work productivity and ADL due to the disease. The absenteeism rate was 10.4% in the past one week and their indirect costs were 2,875.17 Malaysian ringgits (US $701.22) in the past seven days. Significant predictors of higher work productivity and ADL impairment scores were higher disease activity, more frequent SLE flares, lupus nephritis, and hematological involvement of SLE. Patients with higher work productivity and ADL impairment scores were also strongly associated with poor QoL. No ethnic disparities of work productivity and ADL impairment were found.

    Conclusion: Systemic lupus erythematosus significantly affected the overall productivity in work and non-work related activity in our Malaysian multi-ethnic cohort and both impairments were significantly associated with poor QoL.

  6. Ibrahim R, Hussein MZ, Yusof NA, Abu Bakar F
    Nanomaterials (Basel), 2019 Aug 31;9(9).
    PMID: 31480466 DOI: 10.3390/nano9091239
    Carbon nanotube-quicklime nanocomposites (CQNs) have been synthesized via the chemical vapor deposition (CVD) of n-hexane using a nickel metal catalyst supported on calcined carbonate stones at temperatures of 600-900 °C. The use of a Ni/CaO(10 wt%) catalyst required temperatures of at least 700 °C to obtain XRD peaks attributable to carbon nanotubes (CNTs). The CQNs prepared using a Ni/CaO catalyst of various Ni contents showed varying diameters and the remaining catalyst metal particles could still be observed in the samples. Thermogravimetric analysis of the CQNs showed that there were two major weight losses due to the amorphous carbon decomposition (300-400 °C) and oxidation of CNTs (400-600 °C). Raman spectroscopy results showed that the CQNs with the highest graphitization were synthesized using Ni/CaO (10 wt%) at 800 °C with an IG/ID ratio of 1.30. The cyclic voltammetry (CV) of screen-printed carbon electrodes (SPCEs) modified with the CQNs showed that the performance of nanocomposite-modified SPCEs were better than bare SPCEs. When compared to carboxylated multi-walled carbon nanotubes or MWNT-COOH-modified SPCEs, the CQNs synthesized using Ni/CaO (10 wt%) at 800 °C gave higher CV peak currents and comparable electron transfer, making it a good alternative for screen-printed electrode modification.
  7. Yong HY, Bakar FD, Illias RM, Mahadi NM, Murad AM
    Braz J Microbiol, 2013 Dec;44(4):1241-50.
    PMID: 24688518
    The mitogen-activated protein (MAP) kinase pathways has been implicated in the pathogenicity of various pathogenic fungi and plays important roles in regulating pathogenicity-related morphogenesis. This work describes the isolation and characterization of MAP kinase gene, Cgl-SLT2, from Colletotrichum gloeosporioides. A DNA sequence, including 1,633 bp of Cgl-SLT2 open-reading frame and its promoter and terminator regions, was isolated via DNA walking and cloned. To analyze gene function, a gene disruption cassette containing hygromycin-resistant gene was constructed, and Cgl-SLT2 was inactivated via gene deletion. Analysis on Cgl-slt2 mutant revealed a defect in vegetative growth and sporulation as compared to the wild-type strain. When grown under nutrient-limiting conditions, hyperbranched hyphal morphology was observed in the mutant. Conidia induction for germination on rubber wax-coated hard surfaces revealed no differences in the percentage of conidial germination between the wild-type and Cgl-slt2 mutant. However, the percentage of appressorium formation in the mutant was greatly reduced. Bipolar germination in the mutant was higher than in the wild-type at 8-h post-induction. A pathogenicity assay revealed that the mutant was unable to infect either wounded or unwounded mangoes. These results suggest that the Cgl-SLT2 MAP kinase is required for C. gloeosporioides conidiation, polarized growth, appressorium formation and pathogenicity.
  8. Hidayah, N., Abu Bakar, F., Mahyudin, N.A., Faridah, S., Nur-Azura, M.S., Zaman, M.Z.
    MyJurnal
    This article summarises the current methods for total malachite green (MG) detection which is known as a sum of MG and leuco-malachite green (LMG) that has been used extensively in aquaculture as fungicide, dye color in textile and other purposes in food industries. LMG is a reducing form of MG, where the MG is easily reduced due to the photo-oxidative de-methylation process. Nevertheless, the use of MG had become an issue due to its toxicity effects. Many analytical instruments such as HPLC, LC—MS/MS, GC—MS, and spectrometry have been widely used for detection of MG. However, these methods require long time sample preparation and analysis, expensive, use hazardous reagents and indirect measurements. Hence, other analytical methods which are more sensitive, safe, rapid, inexpensive and portable are required. Alternatively, biosensors promise a more sensitive and rapid detection method for MG and LMG.
  9. Nur Aimi, R., Abu Bakar, F., Dzulkifly, M.H.
    MyJurnal
    Nipa sap or air nira is a sweet natural beverage obtained from a type of palm tree, Nypa fruticans.
    It is readily and spontaneously fermented resulting in the development of alcoholic fermentation products. Objective of this study is to determine the volatile compounds (VOCs) responsible for the aroma in fresh and fermented nipa sap. The sap was left for natural fermentation at 30ºC for 63 days. VOCs of the sap were analysed using static headspace gas chromatography-mass spectrometry (GC-MS). Fresh nipa sap contained ethanol (83.43%), diacetyl (0.59%), and esters
    (15.97%). Fermented nipa sap contained alcohols (91.16 – 98.29%), esters (1.18 – 8.14%), acetoin (0.02 – 0.7%), diacetyl (0.04 – 0.06%), and acetic acid (0.13 – 0.68%). Concentration of ethanol in fresh nipa sap increased from 0.11% (v/v) to 6.63% (v/v) during the fermentation, and slightly decreased to 5.73% (v/v) at day 63. No higher alcohols were detected in the fresh nipa sap. Concentration of 1-propanol and 2-methylpropanol were constant throughout the fermentation with average of 0.004 to 0.006% (v/v) and 0.0001 to 0.0009% (v/v), respectively. 3-methylbutanol increased during the fermentation process. The highest concentration (0.001% v/v) was recorded at day 35. This study has shown differences in VOCs types between fresh and fermented nipa sap.
  10. Nakyinsige K, Sazili AQ, Aghwan ZA, Zulkifli I, Goh YM, Abu Bakar F, et al.
    Meat Sci, 2015 Oct;108:125-31.
    PMID: 26115345 DOI: 10.1016/j.meatsci.2015.05.029
    This experiment aimed to determine microbial spoilage and lipid and protein oxidation during aerobic refrigerated (4°C) storage of rabbit meat. Forty male New Zealand white rabbits were slaughtered according to the Halal slaughter procedure. The hind limbs were used for microbial analysis while the Longissimus lumborum m. was used for determination of lipid and protein oxidation. Bacterial counts generally increased with aging time and the limit for fresh meat (10(8)cfu/g) was reached at d 7 postmortem. Significant differences in malondialdehyde content were observed after 3d of storage. The thiol concentration significantly decreased with increase in aging time. The band intensities of myosin heavy chain and troponin T significantly reduced with increased refrigerated storage while actin remained relatively stable. This study thus proposes protein oxidation as a potential deteriorative change in refrigerated rabbit meat along with microbial spoilage and lipid oxidation.
  11. Mohd Zainol, M.K., Abdul-Hamid A., Abu Bakar, F., Pak Dek, S.
    MyJurnal
    The effect of different drying methods on the degradation of flavonoids in Centella asiatica was evaluated. C. asiatica leaf, root and petiole were dried using air-oven, vacuum oven and freeze drier. Flavonoid was determined utilizing reverse-phase high performance liquid chromatography (RP-HPLC). Results of the study revealed the presence of high concentration of flavonoids in C. asiatica leaf, root and petiole, which include, naringin (4688.8 ± 69 μg/100 g, 3561.3 ± 205 μg/ 100 g, and 978.3 ± 96 μg/ 100 g), rutin (905.6 ± 123 μg/ 100 g, 756.07 ± 95 μg/ 100 g, and 557.25 ± 58 μg/ 100 g), quercetin (3501.1 ± 107 μg/ 100 g, 1086.31 ± 90 μg/ 100 g, and 947.63 ± 83 μg/ 100 g) and catechin (915.87 ± 6.01 μg/ 100 g, 400.6 ± 67 μg/ 100 g, and 250.56 ± 18 μg/ 100g). Luteolin, kaempferol and apigenin on the other hand, were inconsistently present in some parts of C. asiatica. Air-oven treatment resulted in the highest total flavonoids degradation followed by vacuum oven and freeze dried with percent degradation of 97%, 87.6% and 73%, respectively. Catechin and rutin were found to be the most stable flavonoids with percent degradation up to 35%, 66% and 76% for freeze dried, vacuum oven and air oven, respectively.
  12. Velu, S., Abu Bakar, F., Mahyudin, N.A., Saari, N., Zaman, M.Z.
    MyJurnal
    Modified atmosphere packaging (MAP) has become a popular method for packaging foods as it can extend the shelf life of food with minimal quality defect. Oxygen, nitrogen and carbon dioxide are the common gases used in MAP, Oxygen and carbon dioxide inclusive as only these two gaseous have the preservative effects on the packed food product. Their effect on microbial changes of any food product throughout storage period is highly depend on type of the product and packaging materials, appropriate gas composition, storage temperature, the ratio between gas and product volume, and hygienic manner during processing and packaging. MAP with highest percentage of carbon dioxide is proven to be more effective than vacuum packaging in inhibiting the growth of spoilage and pathogenic bacteria in many fishery products. This article reviews the consequences of MAP towards microbial changes in fishery products.
  13. Vitamin E in Neuroprotection Study (VENUS) Investigators, Hor CP, Fung WY, Ang HA, Lim SC, Kam LY, et al.
    JAMA Neurol, 2018 04 01;75(4):444-452.
    PMID: 29379943 DOI: 10.1001/jamaneurol.2017.4609
    Importance: Management of painful diabetic peripheral neuropathy remains challenging. Most therapies provide symptomatic relief with varying degrees of efficacy. Tocotrienols have modulatory effects on the neuropathy pathway and may reduce neuropathic symptoms with their antioxidative and anti-inflammatory activities.

    Objective: To evaluate the efficacy of oral mixed tocotrienols for patients with diabetic peripheral neuropathy.

    Design, Setting, and Participants: The Vitamin E in Neuroprotection Study (VENUS) was a parallel, double-blind, placebo-controlled trial that recruited participants from January 30, 2011, to December 7, 2014, with 12 months of follow-up. This trial screened 14 289 patients with diabetes from 6 health clinics and ambulatory care units from 5 public hospitals in Malaysia. A total of 391 patients who reported neuropathic symptoms were further assessed with Total Symptom Score (TSS) and Neuropathy Impairment Score (NIS). Patients 20 years or older with a TSS of 3 or higher and an NIS of 2 or higher were recruited.

    Interventions: Patients were randomized to receive 200 mg of mixed tocotrienols twice daily or matching placebo for 12 months. Patients with hyperhomocysteinemia (homocysteine level ≥2.03 mg/L) received oral folic acid, 5 mg once daily, and methylcobalamin, 500 μg thrice daily, in both groups.

    Main Outcomes and Measures: The primary outcome was patient-reported neuropathy TSS (lancinating pain, burning pain, paresthesia, and asleep numbness) changes at 12 months. The secondary outcomes were NIS and sensory nerve conduction test result.

    Results: Of 391 eligible patients, 300 were recruited (130 [43.3%] male; mean [SD] age, 57.6 [8.9] years; mean [SD] duration of diabetes, 11.4 [7.8] years) and 229 (76.3%) completed the trial. The TSS changes between the tocotrienols and placebo groups at 12 months (-0.30; 95% CI, -1.16 to 0.56; P = .49) were similar. No significant differences in NIS (0.60; 95% CI, -1.37 to 2.65; P = .53) and sensory nerve conduction test assessments were found between both groups. In post hoc subgroup analyses, tocotrienols reduced lancinating pain among patients with hemoglobin A1C levels greater than 8% (P = .03) and normohomocysteinemia (homocysteine level <2.03 mg/L; P = .008) at 1 year. Serious adverse events in both groups were similar, except more infections were observed in the tocotrienols group (6.7% vs 0.7%, P = .04). Results reported were of modified intention-to-treat analyses.

    Conclusions and Relevance: Supplementation of oral mixed tocotrienols, 400 mg/d for 1 year, did not improve overall neuropathic symptoms. The preliminary observations on lancinating pain among subsets of patients require further exploration.

    Trial Registration: National Medical Research Registry Identifier: NMRR-10-948-7327 and clinicaltrials.gov Identifier: NCT01973400.

  14. Siddiquee S, Yusof NA, Salleh AB, Abu Bakar F, Heng LY
    Bioelectrochemistry, 2010 Aug;79(1):31-6.
    PMID: 19945357 DOI: 10.1016/j.bioelechem.2009.10.004
    A new electrochemical biosensor is described for voltammetric detection of gene sequence related to Trichoderma harzianum. The sensor involves immobilization of a 20 base single-stranded probe (ssDNA), which is complementary to a specific gene sequence related to T. harzianum on a gold electrode through specific adsorption. The DNA probe was used to determine the amount of target gene in solution using methylene blue (MB) as the electrochemical indicator. The covalently immobilized probe could selectively hybridize with the target DNA to form a hybrid on the surface despite the bases being attached to the electrode. The changes in the peak currents of methylene blue (MB), an electroactive label, were observed upon hybridization of probe with the target. Peak currents were found to increase in the following order: hybrid-modified AuE and the probe-modified AuE which localized to the affinity of MB. Control experiments with the non-complementary oligonucleotides were performed to assess whether the DNA biosensor responds selectively, via hybridization, to the target. DNA biosensor also able to detect microorganism at the species levels without nucleic acid amplification. The redox current was linearly related to the concentration of target oligonucleotide DNA, ranged from 1-20 ppm. Numerous factors, affecting the probe immobilization, target hybridization and indicator binding reactions are optimized to maximize the sensitivity and reduce the assay time.
  15. Azri FA, Sukor R, Selamat J, Abu Bakar F, Yusof NA, Hajian R
    Toxins (Basel), 2018 May 11;10(5).
    PMID: 29751668 DOI: 10.3390/toxins10050196
    Mycotoxins are the secondary toxic metabolites produced naturally by fungi. Analysis of mycotoxins is essential to minimize the consumption of contaminated food and feed. In this present work, an ultrasensitive electrochemical immunosensor for the detection of aflatoxin B₁ (AFB₁) was successfully developed based on an indirect competitive enzyme-linked immunosorbent assay (ELISA). Various parameters of ELISA, including antigen⁻antibody concentration, blocking agents, incubation time, temperature and pH of reagents, were first optimized in a 96-well microtiter plate to study the antigen⁻antibody interaction and optimize the optimum parameters of the assay. The optimized assay was transferred onto the multi-walled carbon nanotubes/chitosan/screen-printed carbon electrode (MWCNTs/CS/SPCE) by covalent attachment with the aid of 1-Ethyl-3-(3-dimetylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS). Competition occurred between aflatoxin B₁-bovine serum albumin (AFB₁⁻BSA) and free AFB₁ (in peanut sample and standard) for the binding site of a fixed amount of anti-AFB₁ antibody. Differential pulse voltammetry (DPV) analysis was used for the detection based on the reduction peak of TMB(ox). The developed immunosensor showed a linear range of 0.0001 to 10 ng/mL with detection limit of 0.3 pg/mL. AFB₁ analysis in spiked peanut samples resulted in recoveries between 80% and 127%. The precision of the developed immunosensor was evaluated by RSD values (n = 5) as 4.78% and 2.71% for reproducibility and repeatability, respectively.
  16. Norlia M, Nor-Khaizura MAR, Selamat J, Abu Bakar F, Radu S, Chin CK
    PMID: 29912639 DOI: 10.1080/19440049.2018.1488276
    The peanut supply chain in Malaysia is dominated by three main stakeholders (importers, manufacturers, retailers). The present study aimed to determine the levels and critical points of aflatoxin and fungal contamination in peanuts along the supply chain. Specifically, two types of raw peanuts and six types of peanut-based products were collected (N = 178). Samples were analysed for aflatoxins by using high-performance liquid chromatography. Results revealed that the aflatoxin contamination was significantly higher (P ≤ 0.05) in raw peanuts and peanut-based products from the retailers. However, there was no significant difference (P ≥ 0.05) in fungal contamination for both types of peanuts except for the total fungal count in raw peanuts from the retailers. Furthermore, raw peanut kernels from the retailers were the most contaminated ones ranged from
  17. Yeo CC, Abu Bakar F, Chan WT, Espinosa M, Harikrishna JA
    Toxins (Basel), 2016 Feb 19;8(2):49.
    PMID: 26907343 DOI: 10.3390/toxins8020049
    Toxin-antitoxin (TA) systems are found in nearly all prokaryotic genomes and usually consist of a pair of co-transcribed genes, one of which encodes a stable toxin and the other, its cognate labile antitoxin. Certain environmental and physiological cues trigger the degradation of the antitoxin, causing activation of the toxin, leading either to the death or stasis of the host cell. TA systems have a variety of functions in the bacterial cell, including acting as mediators of programmed cell death, the induction of a dormant state known as persistence and the stable maintenance of plasmids and other mobile genetic elements. Some bacterial TA systems are functional when expressed in eukaryotic cells and this has led to several innovative applications, which are the subject of this review. Here, we look at how bacterial TA systems have been utilized for the genetic manipulation of yeasts and other eukaryotes, for the containment of genetically modified organisms, and for the engineering of high expression eukaryotic cell lines. We also examine how TA systems have been adopted as an important tool in developmental biology research for the ablation of specific cells and the potential for utility of TA systems in antiviral and anticancer gene therapies.
  18. Seman WM, Bakar SA, Bukhari NA, Gaspar SM, Othman R, Nathan S, et al.
    J Biotechnol, 2014 Aug 20;184:219-28.
    PMID: 24910973 DOI: 10.1016/j.jbiotec.2014.05.034
    A Pichia pastoris transformant carrying the cutinase cDNA of Glomerella cingulata was over-expressed in a 5L bioreactor (2.0L working volume) under fed-batch conditions. Bioreactor experiments rely on varying selected parameters in repeated rounds of optimisation: here these included duration of induction, pH and temperature. Highest cell densities (320gL(-1) wet cell weight) with a cutinase production of 3800mgL(-1) and an activity of 434UmL(-1) were achieved 24h after induction with methanol in basal salt medium (at pH 5 and 28°C). Characterisation of the cutinase showed that it was stable between pH 6 and pH 11, had an optimum pH of 8.0 and retained activity for 30min at 50°C (optimum temperature 25°C).The preferred substrates of G. cingulata cutinase were the medium- to long-chain ρ-nitrophenyl esters of ρ-nitrophenylcaprylate (C8), ρ-nitrophenyllaurate (C12) and ρ-nitrophenylmyristate (C14), with the highest catalytic efficiency, kcat/Km of 7.7±0.7mM(-1)s(-1) for ρ-nitrophenylcaprylate. Microscopic analyses showed that the G. cingulata cutinase was also capable of depolymerising the high molecular weight synthetic polyester, polyethylene terephthalate.
  19. Akanbi, T.O., Kamaruzaman, A.L., Abu Bakar, F., Sheikh Abdul Hamid, N., Radu, S., Abdul Manap, M.Y., et al.
    MyJurnal
    The activities of lipase produced by five lipases-producing thermophilic bacteria strains (SY1, SY5, SY6, SY7 and SY9) isolated from Selayang Hot Spring in the western part of Peninsular Malaysia were analyzed and compared. SY7 and SY9 had considerably higher lipolytic activities than those of SY1, SY5 and SY6. Thermostabilities of lipase produced by all strains were determined after heating at 80°C for 30 minutes. Strain SY7 retained the highest lipolytic activity of 77%, while others had infinitesimally low thermostability (retaining less than 34% of their original activity) at the same temperature and time. SY7 was chosen for further characterization because it showed exceptionally high lipase activity and thermostability. It was identified as belonging to Bacillus species by the conventional Gram-staining technique, Biochemical tests and Biolog Microstation system. By using 16S rRNA gene sequencing, strain SY7 generated the same expected PCR product with molecular weight of 1500 base pair. It displayed 98% sequence similarity to Bacillus cereus strain J-1 16S rRNA gene partial sequence with accession number: AY305275 and has been deposited in the database of Genbank.
  20. Velu, S., Abu Bakar, F., Saari, N., Zaman, M.Z., Mahyudin, N.A.
    MyJurnal
    The demand for novel antimicrobial agents from natural resources has been increased worldwide for food conservation purpose. In this study antimicrobial activity of musk lime, key lime and lemon were evaluated against various food borne pathogens and spoilage bacteria using disc diffusion test. Type of extraction solvent and concentration level significantly influenced the antibacterial activity of all the extracts. Ethanol extracts of musk lime, key lime and lemon exhibited significant broadest inhibitory activity at 100% concentration level (pure extract) compared to water and juice extracts. 100% ethanol extracts of musk lime (39.7 mm), key lime (26.7 mm) and lemon (32.0 mm) exhibited the largest diameter of inhibition zone (DIZ) against Aeromonas veronii. 100% water extracts of musk lime (25.3 mm), key lime juice extract (23.3 mm) and water extracts of lemon (23.7 mm) was most effective against food spoilage bacteria, A. veronii. The prominent results of the antimicrobial activity from lime, key lime and lemon extracts may attribute them as potential natural food preservatives and could be used in pharmaceuticals field.
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